Help sort shapes in a shape factory. Look at examples of shapes to see if they belong in a polygon group, or set. Examine examples of shapes that do not belong in the set. What features do you think ...

Two-dimensional (2D) shapes are completely flat. 2D shapes can be found printed in a book or on a website. 2D shapes have sides and corners. A rectangle has 4 straight sides and 4 corners. A square is ...

How few corners can a shape have and still tile the plane?” mathematician Gábor Domokos asked me over pizza. His deceptively simple question was about the geometry of tilings, also called ...